The purpose of this project is to examine the movement-related organization of the primary motor cortex (MI) and two closely related motor areas, the supplementary motor area (SM) and the premotor area (PM). The model species that has been chosen for study is the rhesus monkey, because the motor areas have been best characterized in this species. In the first part of this project electrical stimulation, including a refinement to the technique of intracortical microstimulation, is being employed to examine the efferent topography of the three motor areas. In the second part of the project, the relationship between single-unit discharge patterns and learned movements is being studied to determine whether activity in the three motor areas is best related to the location of a target in space or to the limb movements necessary to acquire the target during a visual tracking task. It is the goal of this part of the project to determine the relative preponderances of different physiological-defined cell types in each motor area.